Djokovic progresses in Astana with resounding result
The 71-minute demolition of the world number 34 follows his 64-minute 6-1, 6-1 thrashing of Cristian Garin on Wednesday.
Former world number one Djokovic, who collected his 89th career title in Tel Aviv last weekend, extended his winning streak to six matches with a ruthless display.
"I think my serve worked very well when I needed to get out of trouble in the first set particularly," said Djokovic, who has not dropped serve in his past three matches.
"There were some 30/30 games, and when I broke his serve for 4-2, I faced a break point and I came in, and he had a look at that passing shot and he missed it. The match is decided in these moments."
The 35-year-old Serb had a small scare in the opening set, complaining of pain in a nail which required the intervention of the physiotherapist.
The early exchanges were well contested with Van de Zandschulp threatening to give Djokovic a serious workout.
But 21-time major winner Djokovic kept his composure and built his game on the accuracy of his service, achieving an 84% first-serve success in the first set and offering up just two break point chances in the match, both of which he saved.
Reigning Wimbledon champion Djokovic has now reached the quarter-finals in eight of the nine tournaments he has played in 2022.
He next faces world number 18 Karen Khachanov on Friday as he continues his push for his 90th title and presses for a place in the ATP Finals.
Seventh-ranked Djokovic only needs to finish the season in the top 20 to make sure of a place in the season-ending showpiece.
Khachanov, who reached the semi-finals of the US Open, earlier prevailed 2-6, 6-3, 6-3 against ninth seed Marin Cilic, the player who lost to Djokovic in the Tel Aviv final.
Former US Open champion Daniil Medvedev made the last eight with a comprehensive 6-3, 6-2 win over Emil Ruusuvuori of Finland.
Second seeded Medvedev and Djokovic will meet in the semi-finals should they both come through their last-eight assignments.
Medvedev, however, must first get past Roberto Bautista Agut on Friday. The Spanish veteran boasts a 4-1 career lead over former world number one Medvedev.
The other quarter-finals see third seed Stefanos Tsitsipas tackle Hubert Hurkacz while Andrey Rublev faces Adrian Mannarino.
